U.S. Pat. No. 4,435,344 discloses a heat-insulating paper container (e.g., a cup) fabricated from paper coated or laminated on its outer surface with a thermoplastic synthetic resin film, preferably a low density polyethylene. In addition, the paper is coated on its inner surface with a thermoplastic synthetic resin film such as a high density polyethylene. Heating the container formed from such a paper causes the low density polyethylene on the outer surface of the container to foam while inner surface of the container remains unformed. Although it has been found that a container having a foamed laminate of low density polyethylene on its outer surface imparts excellent heat-insulating properties to the container, the container is still susceptible of improvements in certain areas.
The container described above is typically produced by cutting out a container body member blank as well as a container bottom panel blank from a paper sheet having one surface coated or laminated with low density polyethylene and the opposite surface coated or laminated with high density polyethylene. The container body member blank is formed into the shape of the container and the container bottom panel blank is secured in place at the bottom of the container body in a known manner. The upper edge of the container body member is then curled or wrapped downwardly and outwardly to form a brim on the container. The upper edge of the container body member is typically curled over through an arc of at least 270.degree. which means that in the finished brim, a portion of the curled upper edge of the container contacts the outer surface of the container sidewall. When the container is then heated to cause the low density polyethylene to foam, the foamed polyethylene bonds the brim of the container to the container sidewall. In some instances, this bonding of the brim to the container sidewall can present difficulties.
For example, proposals have been made to place promotional printing, prize information or other forms of indicia under the curled brim of the container so that the promotional printing, prize information or indicia is concealed. By unrolling or unwrapping the curled container brim, the promotional material, prize information or other indicia can be revealed.
With the heat-insulating container construction described above, because the brim is bonded to the container sidewall by virtue of the foaming action of the low density polyethylene, it can be quite difficult to unroll the curled brim. Thus, these types of containers are not well suited to being used in situations in which promotional printing, prize information or other indicia is concealed under the container brim and is adapted to be revealed and rendered visible by unrolling the brim.
In light of the foregoing, a need exists for a container, such as a container having an outer surface layer of foamed thermoplastic synthetic resin film, that is designed to facilitate the unrolling or unwrapping of the curled brim to reveal indicia located under the container brim.